As is well known, steam baking is increasingly appreciated for the quality of the results; for example, it makes it possible to keep many types of food, such as meat, tender, even when they are cooked at high temperatures and in ventilated ovens, that is with forced air circulation.
Steam is generated in these ovens in various ways.
In a first case, the oven is equipped with a specially provided boiler, which is arranged outside the baking chamber. When the water is brought to a boil in the boiler, the steam is conveyed to the baking chamber of the oven. Steam production is constant, but this solution has the drawback of being more complex and cumbersome due to the overall dimensions of the equipment and the necessity of having specially provided connections.
In a second case, steam is generated directly in the baking chamber by spraying water on the heating elements. In this case, the heating elements cool down when the water hits them, and the quality of the steam is affected. To eliminate this problem, the injection of water is normally timed in such a way as to allow the heating elements to resume their steady state temperature. In any case, the quality of the steam generated in this manner is not constant.
Italian Patent application IT PN2009A000057, filed on Oct. 13, 2009 by the same applicant, describes a combined process for the production of steam in a steam-baking oven. The oven is associated with a steam generator and is connected to a water supply. In the initial starting phase, the steam generator is activated until a substantially saturated steam is obtained in the baking chamber; once saturation is achieved, the steam generator is switched off and the steam is generated by water sprayed directly onto the heating elements. The oven includes means for detecting the percentage of humidity in the baking chamber in order to activate suitable control means that periodically switch on the steam generator so as to maintain the steam quality in the chamber substantially constant with respect to a predetermined value. The steam quality is the percentage by mass of steam in a liquid-steam mixture, which may vary between 0 (saturated liquid) and 1 (dry saturated steam), and thus defines the degree of humidity of the steam present in the baking chamber.
With the automatic control of steam quality according to the above-mentioned procedure, the steam present in the baking chamber is perceived by the user as “dry steam”. In this manner, the food is cooked uniformly, without the formation of droplets of water vapor on its surface, which would give the consumer the impression of a “wet” food, or food impregnated with water during the cooking process.
This type of “dry steam”, and thus a steam quality of approximately 1 automatically controlled and stabilized, is particularly suitable to cook certain types of vegetables, as for example cauliflower or spinach; once cooked and removed from the oven, the food, although steam baked, does not appear “wet”, and the pan is dry because the liquid mass consists of particles in suspension that do not settle down, by the effect of gravity, onto the food or on the bottom of the pan.
However, to cook other types of food it is preferable to have an atmosphere in the baking chamber with a higher percentage of water, and therefore a steam quality lower than 1; this type of cooking is required, for example, in the preparation of potatoes, in which an atmosphere with a higher water content makes it possible to have a faster cooking and the finished product is more suitable for the subsequent processes, in particular for the preparation of mashed potatoes.